Medium
S.59 on Vaillant ecoTEC exclusive Combi

Your boiler is temporarily pausing because it cannot detect enough water flowing through the system to heat it safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Waiting time: Water circulation vol. (Minimum circulation water volume)

From this model's manual
Verified against the Vaillant Ecotec Exclusive Combi installation & service manual, page 42.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check that all radiator valves throughout your home are fully openEnsure your system pressure is at the correct level, typically between 1.0 and 1.5 barCheck for any blockages in your external magnetic system filter if one is fitted

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